Lynne Wong's PhD thesis

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Residual EMC/% db 6 3 0 0 10 20 30 40 -3 -6 GAB 7 Hailwood - Horrobin 5 3 1 -1 0 10 20 30 40 -3 -5 Henderson 6 3 0 0 10 20 30 -3 -6 Residual EMC/% db 6 3 0 0 10 20 30 40 -3 Bradley Caurie I 6 3 0 0 10 20 30 40 -3 Smith 6 3 0 0 10 20 30 40 -3 -6 -6 -6 Residual EMC/% db 6 3 0 0 10 20 30 40 -3 -6 Oswin Halsey 6 3 0 0 10 20 30 40 -3 -6 Caurie II 9 6 3 0 0 10 20 30 -3 -6 Residual EMC/% db 6 3 0 0 10 20 30 40 -3 Modified GAB -6 Predicted EMC/% db 30°C 45°C 55°C 60°C Figure 5.11. Residual plots for the different isotherm models of the EMC data of stalk fibre of R 570 aged 52 weeks at temperatures of 30, 45, 55 and 60 o C. 223
Table 5.28. Classification of residual plots for various isotherm models applied to the nine cane components of R 570 aged 52 and 36 weeks. Stalk fibre Stalk pith Rind fibre Rind fines Top fibre Dry leaf fibre Dry leaf fines Green leaf fibre Green leaf fines Isotherm model 52 36 52 36 52 36 52 36 52 36 52 36 52 36 52 36 52 36 GAB R R R R R R R R R R R R R R R R R R Hailwood Horrobin R R R R R R R R R R R R R R R R R R Henderson R R S S R R R R S S S R S S S R S S Bradley R R R R R R R R R R S R R R R R S R Caurie I S S S S S S S S S S S R S S S S S S Smith R R R R R R R R R R R R R R R R R R Oswin R R R R S R S R S R R R S R S R S R Halsey S S S S S S S S S S S R S S S S S R Caurie II S S S S S S S S S S S S S S S S S S Modified GAB R R R R R R R R R R R R R R R R R R R = random, S = systematic For the four remaining models, a comparison of the performance parameters R 2 , P and E s listed in Tables 5.19 – 5.27 showed that, in general, the GAB, Hailwood-Horrobin and modified GAB models all yield comparable R 2 values, however, the modified GAB model gave a slightly lower value of P and E s than the Hailwood-Horrobin, GAB and Henderson models, in that order. Hence, it has been shown that the modified GAB model provides an acceptable description of the isotherms of sugar cane component parts in the range of water activity and temperature studied, with only the exception mentioned above, with GAB and Hailwood-Horrobin models rank a close second followed by Henderson models. It is to be noted that none of the models studied gave a satisfactory fit to the data obtained at 60 °C for dry leaf fibre and green leaf fibre, both aged 36 weeks. This is due to the data obtained as seen in Fig 5.9, both components gave isotherms which were in general less steep than those of the other cane components. The experimental EMC data of the nine cane components aged 52 weeks were compared with the data predicted by the modified GAB, Hailwood-Horrobin and GAB models (see Figs 5.12 – 5.14). Although the modified GAB model was found best to describe the isotherms of the sugar cane component parts at temperatures of 30, 45, 55 and 60 °C, it did not extend beyond water activity of 0.95, whereas the other two did, up to a water activity of one. So, in conclusion, the models which best describe the sorption characteristics of the sugar cane component parts are the Hailwood-Horrobin and the GAB isotherms. In contrast, as mentioned in Section 5.4.1, Han and Wu (2004) found that Nelson’s sorption isotherm model was a good fit for their experimental adsorption data of sugar cane rind. As Nelson’s model involves desorption which was not performed on samples investigated, comparison could not be made. 224
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THE BRIX-FREE WATER CAPACITY AND SO
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dissolved and hydrated waters, and
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ACKNOWLEDGEMENTS I am particularly
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Page 1.5 THE DELETERIOUS EFFECTS OF
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Page 2.2 THE PHENOMENON OF BRIX-FRE
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Page 3.4.3.3 Cane tops 83 3.4.4 Cha
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4.3.3 Temperature at which Brix-fre
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4.6.1 Materials 143 4.6.1.1 Samples
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CHAPTER 6. PROPERTIES OF THE SORBED
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APPENDIX 3. CALCULATIONS LEADING TO
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LIST OF FIGURES Page Figure 1.1. Fi
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Figure 3.1. Glucose and fructose an
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Figure 5.11. Residual plots for the
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total adsorbed water (m) and the pr
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Table 2.18. Moisture content in sug
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Page Table 4.4. Results of the dete
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Page Table 4.24. Analysis of varian
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Page Table 5.13. Table 5.14. Equili
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Table 6.3. Heat of sorption of the
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GLOSSARY OF TERMS Absorption is the
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Filterability of a raw sugar is mea
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Sorption is the generic term used w
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LIST OF MAIN SYMBOLS Symbol Descrip
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s c s Slope of Caurie I isotherm pl
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number of 255, and cane land covere
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Nouvelle Mon In Trésor ustrie and
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Figure 1.3. Cane sampling by core s
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In Mauritius, most of the sugar fac
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are: cane tops, dry and green leave
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1.4 TRENDS IN CANE QUALITY RECEIVED
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campaign was launched to encourage
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The level of extraneous matter in c
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In Australia (Cargill, 1976), cane
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The effect of soil on factory perfo
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leaves increased the level of impur
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• From 1976 to 1980, when the pro
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Clerget purity of molasses 40 Clerg
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CHAPTER 2. IMPACT OF EXTRANEOUS MAT
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Since the extrapolated purity of mo
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Figure 2.1. Jeffco cutter grinder.
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2.1.4 Results The analytical result
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Table 2.3. Analytical results of re
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Table 2.5. Composition of dry trash
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Table 2.7. Predicted factory perfor
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Boiling house recovery 91.0 89.8 89
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0 5 10 15 20 % EM in cane y = 0.572
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% EM in cane 0 5 10 15 20 0 -2 -4 -
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1 y = 0.020 (% D) R 2 = 1.00 = 0.03
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% EM in cane 0 5 10 15 20 0 -2 y =
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esulting in 0.015 unit sucrose loss
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2.2.1 Experimental procedure Cane m
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filter paper, rejecting the first f
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Table 2.9. Effect of increased addi
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Table 2.11. Effect of increased add
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Table 2.13. Effect of increased add
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various components such as stalk fi
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in the presence of dry leaves, if c
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Table 2.17. Moisture content in sug
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CHAPTER 3. SEPARATION OF THE SUGAR
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Table 3.1. It can be seen that the
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Table 3.2. Fibrous physical composi
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R 579 R 570 M 1557/70 M 1400/86 74
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loosen the fibre. The woody core is
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agitate the mixture in the pot, and
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Figure 3.7. Custom-built fibre-pith
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The extraction of fibres starting f
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pre-treatment in a Jeffco cutter-gr
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Figure 3.19. Stalk cake washed free
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not have many dry leaves attached t
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Table 3.5. Masses of cane samples a
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Table 3.7. Masses of cane samples a
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Table 3.9. Masses of cane component
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3 57.6 126.3 23.7 97.2 31.1 53.8 11
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Table 3.12. Material loss (%) from
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3.5.3 Fibre/pith ratios in cane com
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Table 3.15. Effect of extraneous ma
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Snow (1974) investigated the season
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from Figure 2.9 that the change in
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Table 3.18. Fibre % cane results by
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110
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(a). Dry leaf (b). Green leaf (c).
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dry fibre, or a factor, is used in
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Steuerwald (1912) applied sucrose s
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solution/fibre ratio was lowered fr
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leave some residual moisture on the
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instead of 150 g of 10° Brix sucro
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Table 4.2. Determination of Brix-fr
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Table 4.3. Comparison of Brix-free
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Table 4.4. Results of the determina
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In order to test for homogeneity of
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Table 4.7. Results of the repeat de
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The experiment was repeated with th
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e any residual moisture in the samp
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By means of the same technique, Won
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was still hot. Since the filter was
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value determined could be corrected
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Qin and White’s finding was confi
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A sample size of 3.5 g with 75 g co
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Figure 4.4. Fibre samples drying in
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- One large fibre sample (rind) of
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Table 4.18. Brix-free water values/
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Table 4.20. Brix-free water values/
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4.7.3 Statistical analysis It is es
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Table 4.23. Analysis of variance (B
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pointing out that at 52 weeks old,
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The crop of R 570 sampled in 2001 w
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4.7.4. Estimated Brix-free water co
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The main difference in the two sets
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Table 4.27. Predicted Brix-free wat
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4.8 SUMMARY AND CONCLUSIONS An anal
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component parts, and verify the Bri
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3) Thermodynamic, water in equilibr
Page 225 and 226: Langmuir (1916, 1917, 1918) propose
Page 227 and 228: to determine the moisture sorption
Page 229 and 230: Table 5.1. Some commonly used isoth
Page 231 and 232: Lomauro et al. (1985) found that wi
Page 233 and 234: and on agricultural products such a
Page 235 and 236: Bruijn (1963) studied the mass incr
Page 237 and 238: After measuring the EMC of dry corn
Page 239 and 240: approached, that is, either by adso
Page 241 and 242: Table 5.4. Water activity (a w ) of
Page 243 and 244: 5.6.3 Procedure to determine equili
Page 245 and 246: 5.6.4 Results and discussion An exa
Page 247 and 248: Table 5.8. Equilibrium moisture con
Page 249 and 250: Table 5.10. Equilibrium moisture co
Page 251 and 252: Table 5.12. Equilibrium moisture co
Page 253 and 254: 30 o C 45 o C 55 o C 60 o C Water w
Page 255 and 256: m/m of 96% activity, a w (g/100g dr
Page 257 and 258: vaporisation generally decreases fr
Page 259 and 260: 30 o C isotherm 45 o C isotherm 55
Page 261 and 262: 4 0 Stalk fibre 5 0 Stalk pith 5 0
Page 263 and 264: 5.6.4.4 Fitting of sorption models
Page 265 and 266: Table 5.19. Parameters of the sorpt
Page 275: Modified GAB Kuhn Iglesias - Chirif
Page 279 and 280: Stalk fibre Stalk pith Rind fibre 4
Page 281 and 282: 5.6.4.5 Calculated EMC values of re
Page 283 and 284: Table 5.30. Calculated equilibrium
Page 285 and 286: m/m of 96% Table 5.32. Calculated e
Page 287 and 288: Table 5.33. Parameters of the Hailw
Page 289 and 290: CHAPTER 6. PROPERTIES OF THE SORBED
Page 291 and 292: where m is the equilibrium moisture
Page 297 and 298: 6.2 THE NUMBER OF ADSORBED MONOLAYE
Page 299 and 300: 6.3 TOTAL SOLID SURFACE AREA AVAILA
Page 301 and 302: Thus, for each cane component of ea
Page 303 and 304: abscissa. For each moisture level (
Page 307 and 308: A similar procedure was followed to
Page 309 and 310: 10 0 Stalk fibre Stalk pith Rind fi
Page 311 and 312: Moreover, if T β > T hm the proces
Page 313 and 314: Table 6.5. Characteristic parameter
Page 315 and 316: Binding energy/kJ (kg mol) -1 2 0 0
Page 317 and 318: 6.8 CALCULATION OF BOUND WATER AND
Page 319 and 320: The values of K 1 , K 2 and W were
Page 321 and 322: Table 6.7. Separation of the total
Page 323 and 324: Table 6.7. (Contd.) Sample 30 o C 4
Page 325 and 326: 3 0 S talk fibre 4 0 Stalk pith 3 0
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3 0 Reconstituted cane at 30 o C 3
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when water is added to dry wood, wh
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It is evident that in some cases ma
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The number of adsorbed monolayers,
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Data in Tables 2.9 and 2.11 show th
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particular fibre is systematically
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Anon. (1985b). Laboratory manual fo
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Blanchi R.H. and A.G. Keller (1952)
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Day D.L. and G.L. Nelson (1965). De
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Heyrovsky J. (1970). Determination
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Kuhn I.J. (1964). A new theoretical
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Madamba P.S., R.H. Driscoll and K.A
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Prinsen Geerligs, H.C. (1897). Stud
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Sing K.S.W., D.H. Everett, R.A.W. H
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Van der Pol C., C.M. Young and K. D
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Lynne Wong's PhD thesis

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